A study led by UCLA Health Jonsson Comprehensive Cancer Centre investigators found that stereotactic body radiotherapy (SBRT), a form of high-dose radiation delivered in just five sessions, after prostate surgery is safe and as effective as traditional, longer courses of radiation in preventing prostate cancer from returning.

After more than four years of follow-up, researchers found:

• 60% of patients remained free of biochemical recurrence, meaning there were no signs of cancer or rise in PSA, and no need for additional hormone therapy.  
• SBRT without hormone therapy lowered the risk of recurrence compared to conventional radiation.
• Side effects were generally manageable. Serious bowel problems occurred in 7% of patients, and urinary issues in 32%. Using MRI-guided radiation helped reduce urinary side effects even further.
• Most patients maintained their quality of life, with minimal changes in urinary, bowel and sexual health. 

After prostate surgery, some men remain at risk of their cancer coming back.

Radiation therapy can lower this risk, but the standard approach usually involves daily treatments for several weeks, which can be burdensome for patients.

Researchers have been exploring whether SBRT, already a proven option for men who have not had surgery, could also be safe and effective in the post-surgery setting.

Its use has been limited, however, because of concerns about safety and the sensitivity of nearby organs.

The SCIMITAR Phase 2 trial enroled 100 patients at UCLA and the University of Southern California who had undergone a radical prostatectomy and were considered at higher risk of recurrence.

Patients received SBRT in five sessions over roughly 10 days, with some also receiving hormone therapy or lymph node radiation based on physician guidance.

Patients were then monitored for about 4.5 years for cancer recurrence, side effects and quality of life.

These results build on earlier findings, which showed SBRT is safe and convenient over a two-year period.

Together, the studies suggest that SBRT may be a faster, simpler option for men who need radiation after prostate surgery.

“These findings suggest this faster treatment approach could offer an alternative to conventional, longer radiation courses for men at risk of recurrent prostate cancer,” said co-first author Dr. Amar Kishan, professor and executive vice chair of radiation oncology at the David Geffen School of Medicine at UCLA and co-director of the cancer molecular imaging, nanotechnology and theranostics programme at the UCLA Health Jonsson Comprehensive Cancer Centre.

“Importantly, side effects were manageable in a majority of men, particularly with MRI-guided treatment, and most men were able to maintain their quality of life.”

Source: University of California - Los Angeles Health Sciences